1. Field of the invention
This invention relates to a contact development process, in which a toner transporting means is brought into pressure contact with a latent image carrier to develop an electrostatic latent image by a toner.
2. Description of the Related Art
In conventional development processes such as a process disclosed in Japanese Patent Laid-Open Publication No. 118052/80, an image is developed by flying a toner from a toner transporting means to a latent image carrier without bringing these two supporters into contact with each other. In a process of this type, a spherical toner has been used to obtain improved flying ability. It is, however, difficult to obtain a high resolution image by this non-contact development process because the distance (gap) between the latent image carrier and a development electrode is large.
As a so-called contact development process, Japanese Patent Laid-Open Publication No. 114163/82 and No. 226676/88 disclose a process in which a single-component non-magnetic toner is employed. Although a development electrode can give a sufficiently high effect, a toner is charged insufficiently in the above contact development process. Therefore, a development density becomes unstable. In addition, some toner particles are charged to an opposite polarity so that the toner particles adhere to no image portion on a latent image carrier (hereinafter referred to as "fogging").
In order to solve the above problems, a contact development process in which a magnetic toner is used has been newly proposed in Japanese Patent Laid-Open Publication No. 58321/90, the disclosure of which is hereby incorporated by reference. The present invention is to further improve this development process.